The present invention relates to an apparatus 100 and, a method and a computer program for determining a first parameter indicative of a concentration of lycopene. In particular, the invention relates to an apparatus 100 comprising a spectrometer 02, which spectrometer comprises a light source 104 and a detector 106, 108 arranged to measure an optical spectrum via an interventional device 112. This enables determination of a first parameter being indicative of a lycopene concentration. Lycopene concentration may serve as a discriminative feature for different tissue types, such as the prostate organ and associated structures. The apparatus may in a specific embodiment be arranged to determine a second parameter indicative of a tissue type based on a concentration of lycopene. According to a specific embodiment, the apparatus relies on Diffuse Reflectance Spectroscopy (DRS).